Sydney
19.2 Leakage to landscape
Supporting information
a. Urban water supply system overview
The urban water supply system is one of three sub-components of Sydney's urban water system. The three sub-components are the:
- Urban water supply system
- Wastewater system
- Recycled water system.
There are two main sources of water for Sydney's urban water supply system:
Urban water consumption (19.4) was 489,557 ML during the 2011–12 year, representing 48% of all urban water supply system outflows. The remaining urban water was reported as being lost through leakage to landscape (19.2) and operational losses (19.20).
The following figure shows all the inflows and outflows associated with the urban water supply system.
For more detail on a particular flow associated with the urban water supply system, refer to the line item notes.

The Sydney region's urban water supply system using data from Sydney Water Corporation, Shoalhaven City Council and Wingecarribee Shire Council
b. Leakage to landscape
Volumes shown in the following table have been recorded as leakage from the urban water system to the landscape. The total volume of leakage from the urban water supply system was 42,987 ML.
Water authority |
Recorded leakage volume from urban system to landscape (ML) |
Shoalhaven City Council |
283 |
Sydney Water Corporation |
42,241 |
Wingecarribee Shire Council |
463 |
Total |
42,987 |
Data on leakage from the urban water system to the landscape are not available for the systems operated by other water utilities.
Quantification approach
Shoalhaven City Council
Data source
Provided by
Method
The number provided by the council is the total loss and leakage from the urban potable water supply and non-potable water (raw water diverted from the rivers) supply systems. This volume was estimated as 9% of the total consumption via the urban potable water and non-potable water supplies.
Assumptions, limitations, caveats and approximations
- Data represents total leakage and loss from potable and nonpotable water supply systems, as the breakdown between the two supplies is not available.
- Total volume of estimated loss and leakage from the urban water supply system is to be taken as an input to the landscape water store, as the breakdown of leakage components entering landscape and groundwater stores are not available separately.
- The uncertainty estimate is based on the total leakage factor for the whole of the area managed, and may not specifically relate to the City Council area within the Sydney region (i.e. the value provided is likely to be an overestimate).
Uncertainty information
The volume is based on measured data from a sample area and extrapolated to other areas. Estimated uncertainty based on meter accuracy, professional judgment and organisational practice is +/– 5%.
Sydney Water Corporation
Data source
Provided by
Method
Assumptions, limitations, caveats and approximations
- Data represents total leakage and loss from potable and nonpotable water supply systems, as the breakdown between the two supplies is not available.
- Total volume of estimated loss and leakage from the urban water supply system is to be taken as an input to the landscape water store, as the breakdown of leakage components entering landscape and groundwater stores are not available separately.
Uncertainty information
Measured and estimated data used in the water balance for the calculation contribute to uncertainty of leakage volumes. As leakage volumes calculated via a water balance are proportionally small, residual errors tend to be magnified. The uncertainty band on leakage as calculated by an annual water balance is estimated to be about +/– 25% with a 95% confidence limit.
Wingecarribee Shire Council
Data source
Provided by
Method
The value represents the total volume of leakage and losses from the potable water supply system. The volume is based on the water balance method, where potable water production figures from the water treatment plants are configured with the consumption figures obtained by flow meter readings at listed properties.
Assumptions, limitations, caveats and approximations
- Data represents total leakage and loss from potable and nonpotable water supply systems, as the breakdown between the two supplies is not available.
- Total volume of leakage is based on an estimated 11% loss from the system.
Uncertainty information
The volume is based on measured data. Estimated uncertainty based on meter accuracy, professional judgment and organisational practice is +/– 20%.